Fuse



C. T. MCDONALD- FUSE.

APPLICATION FILED JULY 23' I9I9.

1,396,333. Patented Nov. 8, 1921.

T I g iZZ//Z far UNITED STATES CLARENCE T. MCDONALD, OF

PATENT ornca.

CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO CHICAGO FUSE MFG. (10., OF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

FUSE.

Specification ofLetters Patent.

Patented Nov. 8, 1921.

7 Application filed July 23, 1919. Serial No. 312,696.

To all 'whom it may concern:

Be it known that I, CLARENCE T. Mo- DONALD, a citizen of the United States, re siding at and State of Illinois, have invented certain new and useful Improvements in Fuses, of which the following is a specification.

My invention relates to cartridge fuses and more particularly to those of the refillable type. In fuses of this type, especially those having so-called knife blade terminals, it has been found very desirable to use washers or gaskets of some flexible material such as leather in connection with the terminals for the purpose of preventing the escape of burning gases or flame along the terminals in order to reduce the fire hazard.

I have found that these gaskets or washers sometimes form too close or tight a joint with the partslwith which they contact so that they entirely out off the escape of gases from the cartridge and thereby cause the pressure in the cartridge to be built up to such a degree that the cartridge may burst. Especially after the fuse has been blown a few times the gasket or Washer is apt to become hard or stiff and to form too tight a joint.

It is the object of the present invention to of fuse.

In the accompanying drawings, Figure 1' is a perspective view of all the parts of the fuse to which I have applied the principles of my invention, the parts being separated and arranged in order. Fig. 2 is a side view partly in section, of the assembled fuse and Fig. 3 is an end view of the fuse.

In the embodiment of my invention selected for illustration, the tube 9 has metallic heads 10 fixed on its ends which heads have square holes 11 in their ends. The fusible element 12 with the terminals 13 attached to it may be inserted in the car- Chicago, in the county of Cook 45 tridge by holding the terminals diagonal with respect to the square holes, after which by rotating the terminals and fuse element degrees, the shoulders l i will engage the ends of the cartridge and prevent longitudinal displacement of the terminals and g A relatively heavy washer 15 slotted to receive the terminal 13 is placed in position over each terminal and has bosses 16 struck up at the corners of a square and adapted to engage in the corners of the square hole in the end of the cartridge to prevent rotation of the terminals. A gasket 17 of suitable flexible material such as leather is then placed over the washer 15. and a second retaining washer 18 is placed on top of the gasket. The cap 19 having an annular inturned flange 20 is. then washers 18 and 15 screwed down over the and the gasket 17, clamping them firmly in position and completing the assembly of the closure for the end of the cartridge.

In the case of fuses of large capacity, when the fuse element 12 is melted by excessive current, the hot gases produced develop considerable pressure inside the cartridge which may burst the tube 9 or strip off the heads 10 if no means of escape is provided. On the other hand, if the gasket 17 is omitted hot gases or flame will often shoot out from the interior of the cartridge along the surface of the terminals 13. This is objectionable in many cases as it may ignite inflammable material nearby, and in practice it has been found necessary to use the gasket shown.

In the devices of the prior art, the outer retaining member 18 was slotted to receive the terminal in rather close sliding engagement. In these devices, especially after repeated blowings of the fuse, the leather gasket tends to pack into the very narrow crack between the outer retaining member and the surface of the terminal and form a complete seal. When this occurs, the cartridge may be exploded by the pressure developed or sometimes the outer retaining member 18 may be bulged up into a dome.

To obviate this difliculty I- have provided notches 21 cut back over a relatively small portion of the periphery 'of the slot thereby providing spaces adjacent the face of the terminal 13' where the leather gasket is less firmly held than at other points so that it may be flexed away from the terminal at these points by the gas pressure and will never pack or stifi'en so as to produce an entirely gas-tight joint.

This construction eliminates the danger of exploding the entire fuse or bulging up the retaining member so that it has to be hammered out flat again before the fuse is refilled. I have illustrated four rectangular notches, two on each side of the terminal, but it will be obvious that the number, shape and size of the notches may be varied at will.

While I have illustrated a particular embodiment of my invention in connection with a particular type of fuse, it should be clearly understood that the description isonly for purposes of illustration and that no limitation of the scope of the appended claims should be inferred therefrom.

I claim as my invention 2' 1. In cartridge fuses of the typehaving a terminal and having a flexible gasket through which the terminal passes, a retainingmember for said gasket having a slot adapted to receive said terminal and having with a tubular cartridge and a terminal extending into said cartridge, two retainin members each having a slot to receive sai terminal and adapted to form a closure for the end of said cartridge, and a gasket between said retaining members, the outer one of said retaining members being cut away to form notches along a portion of the periphery of its slot. 3. In cartridge fuses of the type having a terminal and a gasket through which the terminal passes, a retaining member for said gasket having a slot adapted to receive said terminal, said slot being shaped to fit said terminal closely'throughout a portion of its periphery and being enlarged to provide clearance space adjacent throughout the remainder of its periphery. In testimony whereof, I have hereunto set my hand.

CLARENCE T. MoDONALD.

said terminal 

